Yes! You need to get the heat up there. At certain temperatures, ICH multiplies like crazy and you dont want to spend too much time at that temperature, IIRC its in the low-mid 80's. There was a time when I had an ICH outbreak in my 55g tank years ago, and I had to keep the temp at 92f for 2.5 weeks. It was wild but I only suffered 1 fatality (my catfish) out of 15 fish.
You do not have to use medication, its not necessary and can kill off any good bacteria you have working for you. Bad, bad, bad.
Mumma was right - use aquarium salt - NOT iodinized salt, in the tank and get those temps up there and keep them stable for 2 weeks. It will get worse before it gets better, thats just the cycle of ICH. But if you keep the temp stable, the salt in the tank, vacuum the substrate every other day to get the ICH out thats fallen to the bottom - you might just come out of this ok.
As far as your fish acting not themselves, you are going to observe with an ICH outbreak - the whole situation is very stressful on fish - this but keep an eye on them. Get the meds out with some water changes and put some carbon in your filters if you have to get it out.
Re: your fish that died that "nothing appeared wrong" remember this: ICH can infest the gills where you cannot see it. There may be not 1 spot on the fishes body, but the interior gills might be infested. Not to mention, the temperature you have the tank at isnt high enough and you need to get aquarium salt in there ASAP.
Hope this helps. This site is great for situations like this, we all have lots and lots of experiences with aquaria crises....lol
